Wireless communication networks are widely deployed to provide various communication services such as telephony, video, data, messaging, broadcasts, and so on. Such networks, which are usually multiple access networks, support communications for multiple users by sharing the available network resources. One example of such a network is the UMTS Terrestrial Radio Access Network (UTRAN). The UTRAN is the radio access network (RAN) defined as a part of the Universal Mobile Telecommunications System (UMTS), a third generation (3G) mobile phone technology supported by the 3rd Generation Partnership Project (3GPP). The UMTS, which is the successor to Global System for Mobile Communications (GSM) technologies, currently supports various air interface standards, such as Wideband-Code Division Multiple Access (WCDMA), Time Division-Code Division Multiple Access (TD-CDMA), and Time Division-Synchronous Code Division Multiple Access (TD-SCDMA). The UMTS also supports enhanced 3G data communications protocols, such as High Speed Packet Access (HSPA), which provides higher data transfer speeds and capacity to associated UMTS networks. High Speed Uplink Packet Access (HSUPA) is a data service offered on the downlink of WCDMA networks.
In a legacy 3GPP UMTS Release 8 HSUPA specification (Rel-8), where the UE is configured to operate in dual carrier (DC) downlink (DL) mode and single carrier (SC) uplink (UL) mode, assuming the primary frequency is f1 and the secondary frequency is f2, the network can configure the UE to perform intra-frequency measurement on frequency f1 and inter-frequency measurement on frequency f2. While performing intra-frequency measurement on f1, the UE may need an intra-frequency neighbor cell list (NCL) and the Active Set (ASET) to do cell measurement and report. While performing inter-frequency measurement on f2, the UE may need an inter-frequency NCL and the Virtual Active Set (VASET) to do cell measurement and report. Notably, there is no real ASET for the “inter-frequency”, i.e. f2, measurements because f2 is considered as non-used frequency. In short in Rel-8, UE has inter-frequency NCL on f2 and VASET on f2 to perform inter-frequency measurement on f2.
In a 3GPP UMTS Release 9 HSUPA specification (Rel-9), with the introduction of DC HSUPA, there are two carriers (frequencies f1 and f2) in both DL and UL and both frequencies are considered as used frequencies. The network can configure the UE to perform intra-frequency measurement on f2. So the UE will maintain two ASETs: one is on the primary frequency, f1, a.k.a. ASET, and the other is on the secondary frequency, f2, a.k.a. the secondary ASET. Also, the network will configure the UE with both intra-frequency NCL on f1 and intra-frequency NCL on f2. UE needs to use intra-frequency NCL on f2 and the secondary ASET to perform intra-frequency measurement and report on f2. In short, in Rel-9, UE has intra-frequency NCL on f2 and the secondary ASET on f2 to perform intra-frequency measurement on f2. As a legacy behavior, the UE may also continue to perform inter-frequency measurement on f2.
However, the HSUPA specifications do not specify how to perform inter-frequency measurement on f2 when the UE is reconfigured from SC UL to DC UL and from DC UL back to SC UL. Therefore, there is a need for technique for performing these UE reconfigurations in compliance with Rel-8 and Rel-9 HSUPA specifications.